/**
 * Copyright (C) 2007 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package safesax;

/**
 * Contains element children.
 */
class Children {

  Child[] children = new Child[16];

  /**
   * Looks up a child by name and creates a new one if necessary.
   */
  Element getOrCreate(Element parent, String uri, String localName) {
    int hash = uri.hashCode() * 31 + localName.hashCode();
    int index = hash & 15;

    Child current = children[index];
    if (current == null) {
      // We have no children in this bucket yet.
      current = new Child(parent, uri, localName, parent.depth + 1, hash);
      children[index] = current;
      return current;
    } else {
      // Search this bucket.
      Child previous;
      do {
        if (current.hash == hash
            && current.uri.compareTo(uri) == 0
            && current.localName.compareTo(localName) == 0) {
          // We already have a child with that name.
          return current;
        }

        previous = current;
        current = current.next;
      } while (current != null);

      // Add a new child to the bucket.
      current = new Child(parent, uri, localName, parent.depth + 1, hash);
      previous.next = current;
      return current;
    }
  }

  /**
   * Looks up a child by name.
   */
  Element get(String uri, String localName) {
    int hash = uri.hashCode() * 31 + localName.hashCode();
    int index = hash & 15;

    Child current = children[index];
    if (current == null) {
      return null;
    } else {
      do {
        if (current.hash == hash
            && current.uri.compareTo(uri) == 0
            && current.localName.compareTo(localName) == 0) {
          return current;
        }
        current = current.next;
      } while (current != null);

      return null;
    }
  }

  static class Child extends Element {

    final int hash;
    Child next;

    Child(Element parent, String uri, String localName, int depth,
        int hash) {
      super(parent, uri, localName, depth);
      this.hash = hash;
    }
  }
}
